Angiopoietin-1 promotes cardiac and skeletal myocyte survival through integrins

SM Dallabrida, N Ismail, JR Oberle, BE Himes… - Circulation …, 2005 - Am Heart Assoc
SM Dallabrida, N Ismail, JR Oberle, BE Himes, MA Rupnick
Circulation research, 2005Am Heart Assoc
Cardiac myocyte loss, regardless of insult, can trigger compensatory myocardial remodeling
leading to heart failure. Identifying mediators of cardiac myocyte survival may advance
clinical efforts toward myocardial preservation. Angiopoietin-1 limits ischemia-induced
cardiac injury. This benefit is ascribed to angiogenesis because the receptor, tie2, is largely
endothelial-specific. We propose that direct, non-tie2 interactions of angiopoietin-1 on
cardiac myocytes contribute to this cardioprotection. We found that mouse C2C12 skeletal …
Cardiac myocyte loss, regardless of insult, can trigger compensatory myocardial remodeling leading to heart failure. Identifying mediators of cardiac myocyte survival may advance clinical efforts toward myocardial preservation. Angiopoietin-1 limits ischemia-induced cardiac injury. This benefit is ascribed to angiogenesis because the receptor, tie2, is largely endothelial-specific. We propose that direct, non-tie2 interactions of angiopoietin-1 on cardiac myocytes contribute to this cardioprotection. We found that mouse C2C12 skeletal myocytes lack tie2, yet dose-dependently adhered to angiopoietin-1 and angiopoietin-2 similarly to laminin, fibronectin, vitronectin, and more than to collagen-I, -III, and -IV. Adhesion was divalent cation-mediated (Mn2+, Ca2+, not Mg2+), blocked with EDTA/EGTA, RGD-based peptides, and select integrin subunit antibodies. Similar findings were obtained with human skeletal myocytes (HSMs) and freshly isolated rat neonatal cardiac myocytes (NCMs). Furthermore, angiopoietin-1 conferred significant survival advantage exceeding that of most cell matrices, which was not fully explained by differences in cell adhesion. Angiopoietin-1 promoted survival of serum-starved C2C12, HSM, and NCM (MTT, trypan blue) and prevented taxol-induced apoptosis (caspase-3). Immobilized and soluble angiopoietin-1 phosphorylated AktS473 and MAPKp42/44, (not FAKY397) in C2C12 more than in endothelial cells and more than did angiopoietin-2 or cell matrices. EDTA, RGD-based peptides, and some integrin antibodies blocked these responses. Angiopoietin-1 activated HSM and NCM AktS473 and MAPKp42/44 survival pathways. We propose that this novel function contributes to developmental and cardioprotective actions of angiopoietin-1 presently attributed to vascular effects alone. Angiopoietin-1 may prove therapeutically valuable in cardiac remodeling by supporting myocyte viability and preserving pump function. The full text of this article is available online at http://circres.ahajournals.org.
Am Heart Assoc